The major objectives of this Co-operative Research Program will be to: (1) develop a vaccine candidate(s) to protect against inhalational tularemia (caused by Francisella tularensis); (2) to develop a polyconal antibody library to be used for passive immunization to ameliorate or prevent acute illness from F. tularensis acquired by the inhalational route and (3) to develop diagnostic systems to detect F. tularensis in clinical specimens and in the environment using immunochemical and/or gene amplification methods. In Project 1, we will prepare and use as vaccine candidates in experimental systems, F. tularensis lipopolysaccharide derived O-polysaccharide and capsular polysaccharides. We will use conjugates and clinically relevant adjuvant and delivery systems to recruit T cell help to enhance immune responses. We will also create peptide surrogates (called mimics) of the two saccharide prototypes and use these for immunization. Mice will be immunized to assess vaccine efficacy against aerosol challenge with F. tularensis. In Project 2, we will design polyclonal antibody expression libraries against F. tularensis and examine the efficacy of passive administration in preventing and treating experimentally induced inhalational tularemia. We will use widely directed polyclonal antibodies to determine overall efficacy, use libraries depleted of putative subversive (blocking) antibodies and generate monospecific polyclonals directed against O-polysaccharides to passively immunize mice and assess protection from aerosol challenge with F. tularensis. In Project 3, we will develop three diagnostic systems, using gene amplification and immunochemical detection, to detect F. tularensis in clinical and environmental specimens. A transcription mediated amplification (TMA) assay will be developed to detect F. tularensis in respiratory secretions and an immunochemical test to detect Francisella antigens in respiratory secretions and urine and for monitoring environmental air samples.